SOLUTION: Hey tutors,I needed a little help in surface area. I know how to find surface ares in different shapes.Although,I dont know how to find missing parts of it (Height,Length etc.) so

Algebra ->  Surface-area -> SOLUTION: Hey tutors,I needed a little help in surface area. I know how to find surface ares in different shapes.Although,I dont know how to find missing parts of it (Height,Length etc.) so       Log On


   

Question 436024: Hey tutors,I needed a little help in surface area. I know how to find surface ares in different shapes.Although,I dont know how to find missing parts of it (Height,Length etc.) so here it is:
The surface area of a rectangular prism is 812cm%5E2.The width is 11cm and the length is 20cm.What is the height of the rectangular prism.
What iv'e tried:
formula 2B%2BPh....Yea...I'm getting nowhere -_-...Thanks!
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
The surface area of a rectangular prism is 812 sq/cm.
The width is 11cm and the length is 20cm.
What is the height of the rectangular prism.
:
the surface area formula
2(L*W) + 2(L*H) + 2(W*H) = S.A.
so we have
2(20*11) + 2(20*H) + 2(11*H) = 812
Simplify, divide by 2
(20*11) + (20*H) + (11*H) = 406
220 + 20H + 11H = 406
31H = 406 - 220
H = 186%2F31
H = 6
:
:
I'll let you check this in the surface area formula